Utilizing cracked gas oil



United States Patent UTILIZING CRACKED GAS OIL Stanford J. Hetzel, Cheltenham, Pa., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New ersey No Drawing. Original application June 15, 1951, Serial No. 231,897. Divided and this application June 5, 1952, Serial No. 291,991 r Claims. (Cl. 260-312) thermal or catalytic cracking, of which the products inelude cracked gasoline and a heavier fraction, cracked gas oil. The starting material to which the present invention is applied is a material boiling through the range 510 F. to 575 F. and comprisingthe. aromatic .con

stituents which are normally present in a cracked gas oil.

Within this definition of starting material are included: cracked gas oils as obtained directly from distillation of cracking products, such gas oils having an initial boiling point not substantially higher than 510 and a final boiling point not substantially lower than 575 F.; and aromatic concentrates obtained from such cracked gas oils and having boiling range specifications as speci fied above. Such aromatic concentrates can be obtained by means known in the art, e. g. by selectively adsorbing the aromatic constituents on silica gel.

Thus, the starting material according to the present invention contains a Wide boiling range mixture of aromatic compounds of the type ordinarily found in cracked gas oil, and may or may not also contain substantial, sometimes major proportions, of nonaromatic constitutents, i. e. saturated and olefinic constituents.

The boiling range of the starting material canbe much wider than 510 F. to 575 F., but the starting material should contain a substantial proportion of constituents boiling within the 510 F. to 575 F. range, and preferably contains at least 30 percent of such co n stituents.

Cracked gas oil for use according to the present invention can be a product obtainedeither from cracking a previously uncracked stock, or from cracking a previously cracked recycle stock. Products obtained from the latter type of cracking operations have generally higher aromatic contents and are therefore somewhat preferred for use according to the present invention.

Cracked gas oil, when used as a recycle stdck for further cracking, becomes more refractory to cracking each time it is cracked and eventually becomes so refractory that it is not economical to crack it, again. Nomfore satisfactory use than as a fuel has been found previously for refractory gas oils of this type. It is highly desirable to find some means for making more valuable products from such gas oils. g

According to the present invention, starting materials comprising cracked gas oils or aromatic concentrates therefrom are contacted with dilute nitric acid at ele-J vated temperature to obtain saponifiable reaction products. It has been found that large yields can be obtained of mixtures of saponifiable materials, which mixtures are capable of esterifying low molecular weight alkyl alcohols to form wide boiling range mixtures of esters which are, despite their wide boiling range, highly satisfactory plasticizers for vinylidene polymers.

According to the invention it is for several reasons preferred to use as starting material a cracked gas oil without previously removing nonaromatic constituents therefrom. First, it has been found that the nonaromatic constituents do not interfere with the formation of saponifiable materials, so that the expense of removing them can be spared. Furthermore, the yields of saponifiable materials are generally substantially higher when the preferred starting material is used indicating probably that some proportion of the nonarornatic constituents reacts to form saponifiable materials. Furthermore, the reaction products obtained are considerably more fluid, and therefore easier to handle in commercial apparatus when the preferred starting material is used.

In contacting hydrocarbon starting materials with nitric acid according to the invention, it is preferred that theconcentration of the nitric acid not exceed 40 percent, in order that nitration be avoided. The concentration is preferably at least about IOpercent. Some varia ,tion from these, concentration limits can be used in particular instances. The concentration of the nitric acid generally declines during the course of the reaction, and

.it is sometimes desirable to add nitric acid to counteract tendency.

The relative amounts of nitric acid and of hydrocarbon material which are contacted according to the invention can vary. Preferably, the total amount of HNOs usedper mole of aromatic hydrocarbon is at least about 2 moles, i. e. about 126 weight units. The mole ratio of HNOa to hydrocarbon material is preferably 2-8, more preferably 3-5. Preferred operation is to contact hydrocarbon material initially with one portion of the nitric acid'and to add the rest subsequently during the course of the reaction, the total amount of nitric acid .used preferably being as specified above.

The temperature at which the nitric acid and hydrocarbon material are contacted is preferably Within the approximate range 160 F. to 250 F. If the contact ing is performed at atmospheric pressure, the temperature is more preferably in the neighborhood of the boil ing point of the aqueous phase. It higher temperatures are used,;the contacting is performed at elevated presoxides are recovered for re-use, and the concentration of on the weight of the aromatic constituents of the hydro carbon charge material, can be obtained in 10 hours. With longer reaction times, yields of weight percent or greater can be obtained.

- Catalysts can be used in the reaction, e. g. manganese dioxide, vanadium oxide, ammonium vanadate, or other suitable catalyst. Fresh oxygen can be supplied to the contacting zone during the course of the reaction, it desired.

-The reaction products obtained according to the inveiitiori generally comprise three layers: an upper oil layer, nios'tly ufireatedhydrocarbon; an intermediate aqueous layer; and a lower tarry layer; mostly saponifiable material. The tarry layer is generally a caked s'olid when aromatic concentrates from cracked gas oil are used as starting materials, and is generally a liquid layer when cracked gas oilitself without removal of nonaromatics is used as starting material. In someinstances, particularly with "relatively long reaction times, the aqueous layer contains in suspension substantial quantities of crystalline solid iniiterial, which probably comprises carhoxylic aeid.

The valuable saponifiable materials produced by the reaction are mostly in the layer, but are also contained iii the upper-oil-layei' to a small degree. The upper oil layer and the tarry layer can be separated from the aqueous layer, and the saponiiiable materials in either the oil or the tarry-layer or both canbe deoiled, either together or separately. Alternatively, the upper oil layer or the tarry oil layer or both, either together or separately, can be esterified, and a wide boiling range mixture of esters separated from the crude esterification products. It is preferred; however, to deoil the sapo'nifiable materials before esterification, since in this way vaporization of large quantities 6r hydrocarbon from the crude esterificanon products is rendered unnecessary. V

Saponifiable means can if desired be recovered from the yellow Crystalline solids, if any such solids appear in the aqueous pha'se'. p I Y Deoiling of the saponifi'able material can be "accomplished by saponifying theupper oil layer or the tarry oil layeror both, either together or separately, and contacting the saponifi'ed product with a selective solvent for hydrocarbon, e. g. diethyl ether, petroleum ether, etc. The aqueous layer remaining after such extraction can then be acidified whereupon a sludge comprising the desired saponifiable material is precipitated. The sludge is separated from the aqueous phase and further purified if desired. In any event, .the product obtained is a valuable mixture of saponifiable materials obtained from a wide boiling range starting material. v I x The product obtained is generally a black viscous liqnid or black low-melting solid. When aromatic 'concent'r'ates from 'c'rackedga's 'oil are used as starting materials, the product is generally a low melting solid 'at ordinary temperatures. When cracked gas oil itself is used, the product is generally a viscous liquid at ordinary temperatures. v

The chemical constitution of the product obtained is unknown. The action 'of nitric acid on various 'hydrocarbons is sufficiently complex that the product can probably be assumed to be a complex m'ixtt'fe. Since Cracked gas oils generally contain substantial quantities of alkylated naphtha1enes','itis possible that the product contains naphthoic acid and alkyl naphthoic acids in some proportion, but the invention is not to be limited by any theory.

The product obtained can 'be esterified with an alkyl alcohol having 1 to 8 carbon atoms. The method of esterification employed can be 'any suitable known method, for example, the esterification canbe accomplished by refluxing together approximately one mole-of the alcohol with 200 grams of the mixture of acidic materials in the presence of a solvent and a catalyst if desired. An excess of the alcohol can be used, the excess acting as 'a thermostatic solvent. The desired product can be obtained from the esterification reaction products, 'for example, by vacuum distilling the products to obtain a fraction higher boiling than any of he'compofiems of the original reaction mixture. This fraction comprises a wide boiling range mixture of esters. Alcohols whioh can be used in the esterification include methyl andethyl 'alcohol and propyl, butyl, amyl, hexyl, heptyl, and octyl alcohols,

"resihs are illtls'tr either straight chainor branched chain. The alcohols may be substituted with noninterfering substituents.

As stated above, the esterification can be conducted in the presence of unreactcd hydrocarbon materials, in which case the hydrocarbons can be distilled from the esterification products, and the ester product mentioned above can then be distilled as a heavier fraction.

Esterifications performed as described give remarkably high yields of materials suitable for plasticizing vinylidene polymers. Although the acidic materials used in the esterification are most likely highly complex, they are apparently free f rommaterials which would substantially interfere in the esterification or in plasticizihg of vinylidene polymers.

The Wide boiling range mixtures of esters obtained as described above have been found to be highly satisfactory plasticizers for vinylidene polymers.

Vinylidene polymers, as contemplated herein, include homopolymers, copolymers, or interpolymers of vinyiidene monomers, i. e. monomers containing a vinylidene (CHz=CH group in the molecule. Examples of vinylidene monomers in'clude styrene, substituted styrenes, vinyl naphthalene, acrylic acids, acrylic acid este s such as methyl acryla'te a'nd methyl methacrylate, vinylidene halides, vi riyl halides, acrylonitrile, vinyl acetate, vinyl ben- -zoate, vinyl capr'oate, divinyl succinate, vinyl acrylate, vinyl ethyl ether, vinyl butyl ketone, etc. Other vinyiidone polymers can he plasticized by the esters of the preseht invention, such as the resins obtained as a result of reaetioii be ween polyvinyl alcohol and aldchydes. Polyvinyl formal,polyvinyl acetal, and polyvinyl butyral ave of the latter group of resins.

The est'ers contemplated by the present inventioncan be used as vinylidene polymer plasticizers either alone or in combination with known plasticizers, such as dio ctyl phthalate, dibu'tyl emanate, tricr'esyl phosphate, and the like.

The proportion or ester to polymer in compositions ac-.

cording to the present invention can vary; in most cases, 20 to lSQ parts by weight of ester per parts of polymer are suitable proportions. Preferred proportions are 40 to 75 parts by weight of ester per 100 parts of polymer.

The ester mixture can be incorporated with the vinyl polymer in any suitable manner, e. g. by milling, molding, dissolving together in solvents, etc.

The following examples illustrate the invention:

Example I In this example, an aromatic concentrate from a catalytically cracked "gas oil was contacted with dilute nitric acid according to the invention. The cracked gas oil was a second pass catalytic gas oil obtained by cracking recycle stock. The aromatic concentrate was prepared by percolating the gas 'oil through a bed of silica gel, and recovering theadsorbed aromatic constituents by the use of a deso'rbing agent according to a method known in the art.

The catalytic gas oil prior to removal of nonaromatic constituents had a boiling range of about 480 F. to about 600 F. and had the following approximate proportions:

400 grams of the aromatic concentrate were admixed with nitric acid (10 percent concentration) the resultingmixture Was heated for 94 hours at about 212 'F. under refluxingc'oiiditiom. The total amount of 10% awe-am S nitric acid used during the 94 hour period'was eight liters. At the end of the 94 hour period, the reaction products were cooled whereupon three main phases appeared in the products: an upper oil layer; an intermediate aqueous layer containing yellow crystalline solids insuspension; and a dark solid cake on the bottom of the reaction zone. The two upper layers 'were decanted, and the remaining cake was saponified with caustic-soda. Unsaponifiable material was removed fromtlie sap'onified products by extraction with diethyl ether' to obtain an aqueous raflinate containing soaps of 'the desired acidic product. The ratfinate was acidified withjhydrochloric acid and extracted with diethyl ether. The extract from the second ether extraction was washed with water and distilled to remove ether and leaveas residue 357 grams of a black low-melting solid constituting the desired mixture of saponifiable material's. Assuming an average molecular weight of 180 for the charge material, and assuming a monocarboxylated product, the mole percent yield of saponifiable materials in the product mixture was about 77 percent. This does not represent the total yield of saponifiable materials, since 116 grams of yellow crystalline solids were recovered by filtration of'the aqueous layer of the reaction products, and'these solids were found to contain substantial proportions of saponifiable materials.

This example shows that high yields of saponifiable materials can be obtained from aromatic' concentrates from cracked gas oils by contact with nitric acid accord ing to the present invention. i

Example 11 3 In this example, the same gas oil as :in iExample l -was contacted with nitric acid without previous removal of nonaromatic constituents. 200 grams of the gas "oil were admixed with percent nitric acid-and the resulting mixture was heated for 75 hours at about 2'l2 F. under refluxing conditions. The total amou'nt of 10' percent nitric acid used was four liters. tion product, three main phases appeared: an upper layer, an intermediate aqueous layer containing yellow crystalline solids in suspension, and a lower, liquid, tarry oil layer. The entire reaction product was filtered to remove the crystalline solids. Saponifiable materials were recovered from the filtrate by the saponification, extrac tion, and acidification procedure described in Example I. The saponifiable product mixture obtained weighed 80 grams and was a black, very viscous liquid. The mole percent yield based on the aromatics in the charge material, was about 85 percent, exclusive of the yellow crystalline solids, of which 18 grams were obtained.

This example shows that the yield of saponifiable material can be greater when cracked gas oil is treated according to the present invention WlthOjlt previous removal of nonaromatics than when an aromatic concentrate from cracked gas oil is treated.

Example 111 In this example, a first pass" catalytic gas oil obtained by cracking a previously uncracked stock, was contacted with dilute nitric acid, without previous re moval of nonaromatic constituents. The gas oil had a boiling range of about 420 F. to about 670 F. and containing about 36 percent aromatic hydrocarbons. The relative proportions of the various types of aromatic hydrocarbons were about the same as in the gas oil treated in Example II. The contacting conditions were essentially the same as those employed in Example II except that the quantities of materials, though used in the same proportions, were twice as great. The mole percent yield of the saponifiable materials recovered from the filtrate was about 90 percent. In addition 43 grams of yellow crystalline solids were obtained.

This example shows that high yields of saponifiable Upon cooling the reac materials can be obtained from first pass cracked gas oil as well as from second pass cracked gas o'ils. I

Example IV In this example, a wide boiling range ester mixture was prepared according to the invention. The alcohol used was n-butyl alcohol. The acidic material used was a black low-melting solid material prepared, in a manner similar to that described in Example I, from an aromatic concentrate from second pass catalytic gas oil. 84 grams of the acidic material were refluxed with cc. of n-butyl alcohol for 10 hours in the presence of 5 cc. of concentrated sulfuric acid as catalyst. At the end of the 10 hour period, the reaction products obtained were vacuum distilled to obtain as esterification product, a fraction boiling between C. and 240 C. at 2 mm. Hg and weighing 42.5 grams. 40.5 grams of residue were obtained from the distillation.

Example V In this example, a wide boiling range mixture of 2- ethyl hexyl alcohol esters was prepared according to the invention from an acidic material obtained, in a manner similar to that described in Example I, from an aromatic concentrate from second pass catalytic gas oil. 100 grams of the mixture of acidic materials were refluxed together with 75 grams of 2-ethy1' hexanol for 10 hours in the presence of 250 cc. of xylene and 5 grams'of paratoluene sulfonic acid. Water from the esterification was removed continuously in a Dean-Stark tube. At the end of the 10 hour period, the reaction products obtained were distilled anda fraction boiling between 172 C. and 275 C. at 23 mm. Hg was taken as the desired product.

- Example VI In this example, a composition comprising polyvinyl chloride plasticized'with a wide boiling range mixture of esters of n-butyl alcohol was prepared. The mixture of esters was that prepared as described in Example IV. 76 parts by weight of a polyvinyl chloride resin known commercially as Geon 101 were mixed together with about 1.2 parts by weight of lead carbonate and about 0.6 part by weight of stcaric acid in the dry state by ball milling. About 52 parts by weight of the mixture of esters were added in a cake mixer and the mass stirred thoroughly until good mixing was obtained. This mass was then fused on a 3" x 8 rubber mill whose rolls were heated to a temperature of about 285 F. The

, banded material was out several times from each side Example VII In this example, a composition comprising polyvinyl chloride plasticized with a wide boiling range mixture of esters of Z-ethyl hexanol was prepared. The mixture of esters was similar to that prepared as described in Example V. 52 parts by Weight of the mixture of esters were fused together with 76 parts of Geon 101 in a manner similar to that described in Example VI. The plastic sheet obtained had good appearance, odor, flexibility, strength, and drape, and no tendency for exudation of plasticizer from the sheet was observed.

This example shows that Z-ethylhexyl esters as well as n-butyl esters, of acidic materials as herein contemplated are good plasticizers for polyvinyl chloride resin.

Substantially similar results are obtained when the esters as herein contemplated are used to plasticize other vinylidene polymers, such s P y y Metal, polym of styrene, methyl methacrylate, vinylidene chloride, acrylonitrile, vinyl acetate, divinyl adipate, vinyl ethyl ether, etc.

The. invention claimed is:

1. A- vinylidine polymer plasticized with a mixture of esters of an alkyl alcohol having 1 to 8 carbon atoms with a mixture. of acidic materials prepared by contacting with nitric acid at reactive temperature within the approximate range from 160, F. to 250 F., a hydrocarbon material boiling. through the range 510 F. to 575 F., selected from the group consisting of cracked gas oil and aromatic fractions separated from cracked gas oil, said mixture of esters boiling through a major proportion of the range from 160 C. to 240 C. at 2-3 mm. Hg.

'2. Composition according to claim wherein vinyl polymer is a vinyl halide polymer.

3. Composition according to claim 10 wherein vinyl polymer is polyvinyl chloride.

4. Composition according to claim 1 wherein alcohol is n-butyl alcohol.

5. Composition according to claim 1 wherein alcohol is 2-ethyl hexyl alcohol.

6. Method for plasticizing a vinylidene polymer which comprises milling together such polymer and a mixture of. esters of .an alkyl alcohol having 1 to 8 carbon atoms with a mixture of acidic materials prepared by contacting with nitric acid at reactive temperature within the approximate. range from 160 F. to 250 F. a hydrocarbon material boiling through the range 510 F. to 575 E, selected from the group consisting of cracked gas oil and aromatic fractions separated from cracked gas oil, said mixture of esters boiling through a m jor proportion of the range from 160 C. to 240 C. at 2-3 mm. Hg.

7. A vinyl polymer plasticized with a mixture of esters obtained by csterifying an alkyl alcohol having 1 to 8 carbon atoms with a mixture of acidic materials prepared by contacting with nitric acid, at a temperature in the approximate range from 160 F. to 250 F., a hydrocarbon material boiling through the range 510 F. to

said

said

said

said

R s ec d tram he r up Kms fi ing o cracked a a l nd a qmat s t ast e ed m rac ed a ai st it in he P u t I suc a go obtain an aqueous layer and therebeneath an immiscible, acidic layer, and separating. said acidic layer constituting said acidic materials from the other products, said mixture of esters boiling through a major proportion of the range from C. to 240 C. at 2-3 mm. Hg.

Y 8. A vinyl halide polymer plasticized with esters of a butyl alcohol with a mixture of acidic materials prepared by contacting with nitric acid at reactive temperature within the approximate range from 160 F. to 250 F. an aromatic fraction separated from cracked gas oil, said fraction boiling through the range from 510 F. to 575 F., said esters boiling mainly within and through the range from 160 C. to 240 C. at 2 mm. Hg.

9. A vinyl halide polymer plasticized with esters of an octyl alcohol with a mixture of acidic materials prepared by contacting with nitric acid at reactive temperature within the approximate range from 160 F. to 250 F. an aromatic fraction separated from cracked gas oil, said fraction boiling through the range from 510 F. to 575 F. said esters boiling mainly within and through the range from 172 C. to 275 C. at 2-3 mm. Hg.

10. A vinyl polymer plasticized with a mixture of esters of an alkyl' alcohol having 1 to 8 carbon atoms with a mixture of acidic materials prepared by contacting with nitric acid at reactive temperature within the approximate range from 160 F. to'250" F., a hydrocarbon material boiling through the range 510 F. to 575 F selected from the group consisting of cracked gas oil and aromatic fractions separated from cracked gas oil, said mixture of esters boiling through a major proportion of the range from 160 C. to 240 C. at 2-3 mm. Hg.

References Cited in the file of this patent UNITED STATES PATENTS 2,157,697 Hagedorn May 9, 1949 

1. A VINYLIDINE POLYMER PLASTICIZED WITH A MIXTURE OF ESTERS OF AN ALKYL ALCOHOL HAVING 1 TO 8 CARBON ATOMS WITH A MIXTURE OF ACIDIC MATERIALS PREPARED BY CONTACTING WITH NITRIC ACID AT REACTIVE TEMPERATURE WITHIN THE APPROXIMATE RANGE FROM 160* F. TO 250* F. A HYDROCARBON MATERIAL BOILING THROUGH THE RANGE 510* F. TO 575* F., SELECTED FROM THE GROUP CONSISTING OF CRACKED GAS OIL AND AROMATIC FRACTIONS SEPARATED FROM CRACKED GAS OIL, SAID MIXTURE OF ESTERS BOILING THROUGH A MAJOR PROPORTION OF THE RANGE FROM 160* C. TO 240* C. AT 2-3 MM. HG. 